By R Krishnan
The author is Programme Manager, Center for Climate Change Research, Indian Institute of Tropical Meteorology, Pune. krish@tropmet.res.in

The south Asian monsoon rains contribute to 75-80 per cent of the region’s annual precipitation. Thus the response of the monsoon hydrological cycle to global climate change becomes an issue of major concern.

The South Asian monsoon circulation sustains the lives of over one fifth of the world’s human population whose water supply is almost entirely dependent on the seasonal summer monsoon during June to September (Fig 1a). While on an average the seasonal monsoon rains contribute nearly 75–80 per cent of the annual precipitation in the region, their year-to-year variations have important implications. How the regional monsoon hydrological cycle might respond to global climate change thus becomes an issue of major concern....